1. Field of the Invention
The present invention relates to a process and a mold for producing a multilayer molded article having good appearance with no wrinkles or breakage of a skin material.
2. Description of the Related Art
Resin molded articles are widely used in many products including automobiles and household electric appliances, since such molded articles are economical and light and have good moldability.
Since the resin molded articles have some drawbacks such that they have poor appearance or cool feeling and that they are easily flawed, it is desired to provide resin molded articles having good surface properties such as better decoration and soft feeling properties.
Although many attempts have been made to provide such desirable resin molded articles, it is impossible for a single kind of resin to have satisfactory moldability and strength and also to provide a molded article having good surface properties.
Then, presently, at least two materials having different functions are composited to produce a multilayer molded article comprising a resin body and a skin material.
As a method for producing the multilayer molded article, there are proposed a method comprising adhering the skin material to the resin body with an adhesive and a method comprising providing a resin melt and the skin material in a cavity formed in a mold consisting of male and female molds and closing the male and female molds whereby the molding of the resin and covering with the skin material are simultaneously accomplished.
However, by the first method, it is very difficult to adhere the skin material on the molded article having a complicated structure without causing wrinkles of the skin material.
In the second method, the air trapped between the skin material and the mold is compressed by the mold closing action, whereby the skin material is wrinkled as shown in FIG. 1A, or the shape is deformed as shown in FIG. 1B since the resin melt is not sufficiently filled, or the skin material is broken so that the resin flows out as shown in FIG. 1C. Therefore, molded articles having little or no commercial value tend to be produced.